This invention relates to silicon wafers which are used in the manufacture of semiconductors, and more particularly, to a wafer cushion which bears down upon wafers within the shipper as well as securing the position of a wafer carrier, when used, within the shipper.
Wafers used in the semiconductor manufacturing process are typically made of silicon or gallium arsenide. The wafers are rather brittle and delicate in nature in that they are easily susceptible to breakage. Silicone wafers must also be kept in a clean environment free of dust and particulate matter. Foreign particulates interfere with the circuitry typically etched on the wafers which is extremely fine.
The silicon wafers undergo many stages of processing and it may be desirable to store and/or transport the silicon wafers during or after any or all of the processing steps. In such instances, the silicon wafers are often loaded into sealable shippers or shipping containers that will protect the brittle delicate wafers against damage and particular contamination. The following U.S. patents disclose such shippers: U.S. Pat. Nos. 4,043,451; 4,450,960; and 4,520,925.
Known past shippers do have many deficiencies which may result in a low yield of semiconductors from the silicon wafers contained within the shippers. That is, the wafers within known shippers are often not secured or fixed within the shippers resulting in breakage and further contamination of adjacent wafers. Furthermore, the wafers must be secured and not subjected to rubbing against any surfaces as such action will further cause particulate contamination and damage to the circuitry etched on the wafer.
Referring to FIGS. 1 and 2 as a matter of further background, wafers 8 typically have a peripheral edge 10 which either may be the flat indexing edge 12 or the round peripheral edge 10. The top edge 14 has a centerline which is used as a reference in this case.
Wafers 8 often are supported, carried, stored and transported in wafer carriers 16 as are well known. Wafer carriers or baskets 16 generally have an open top 18, sidewalls 20 with wafer supporting ribs, a front wall 22 with an indexing H-bar 24, a rear wall 26 and a top flange 28 along the sidewalls 20.
Shippers, as stated, are well known as the one illustrated in this case marked with the reference numeral 32. Shipper 32 has a bottom receptacle or cavity 34 with a carrier indexing structure or rib 36 located therewithin. Shippers 32 may also have a rib structure within their bottom cavity to support wafers without the need for a wafer carrier 16. Shipper 32 also has a top or cover 38 with an interior ceiling 40. The present invention contemplates ceiling 40 to have elongate slots 42 running longitudinally and having several transverse shorter slots 44 adjacent to slots 42. An alternative shipper 46 has a cover 48 also with a ceiling 50 having downwardly protruding buttons 52.
There is a need for a wafer cushion which may be used within a wafer shipper to supportably engage the wafers within the shipper to prohibit wafer movement which otherwise may generate particulate contamination and/or breakage. When a wafer carrier or basket is used with such a shipper, such a wafer cushion should secure the carrier within the shipper which otherwise may further increase contamination, particulate generation and breakage of the wafers.